INTROPICA

5-18

Authors: Andrés Vélez-Pereira, Yiniva Camargo Caicedo, Sandra Rocío Balaguera Rincones

Different stages during the degradation of municipal solid wastes (MSW) in landfills can contribute to the emission of bioaerosols, which may represent a health hazard causing allergic, respiratory and infectious diseases. However, the studies related to the generation of airborne bacteria in landfill sites in Colombia are still scarce. Therefore, this study was aimed to establish the spatial and temporal distribution of airborne bacteria generated during the final disposal of MSW at the Palangana landfill site, located at Sant a Marta district. To achieve this aim, three monitoring locations were selected at different operations taking place in the landfill site, and following the wind direction; these locations corresponded to the active cell, the close cell and the leachate collection pond, where six monitoring campaigns were performed both in the morning and afternoon. Airborne bacteria were collected on standard plate count agar using a two-stage cascade impactormodel 10-800 (Tisch Environmental, Inc.), operating at 28,3 l/min during 3 min (sampling time) and located at 1,5 m height. Plates were incubated for 48 h at 28°C for colony counting. The highest airborne bacteria concentration in the morning sampling was obtained at the leachate pond (2.320 CFU/m3), whereas in afternoon samplings the highest concentration as obtained in the active cell (3.545 CFU/m3). Besides, there was higher concentration of breathable bacteria compared to the sedimentable bacteria, confirming the health hazard for site workers due to the exposure to the airborne bacteria that can reach the respiratory system.

29-46

Authors: Marisabel Ureta Adrianzén

The species richness of Peruvian Rainforest is immense considering the great diversity of microclimates and land surfaces; this makes the central forest of our country an interesting and particular place. That is the case of the Central Forest in Oxapampa (Peru), located in the eastern slopes of the Andes. The Missouri Botanical Garden-Perú possesses samples collected since 2004 and currently 35 000 botanical specimens have been deposited in the Herbario de la Selva Central - HOXA (Herbarium of Central Forest-HOXA). For the present study, a taxonomical review was performed for the Myristicaceae family; consequently 550 specimens were distinguished, determined and identified in 4 genera and 14 species. The most important species found include Compsoneura, Iryanthera, Otoba and Virola. Among other aspects, it is central to point out that the largest geographical distribution of the family Myristicaceae was found in lowland Amazonian forests. However, this study collected species from transitional forests; such is the case of Compsoneura sprucei, which also comprise a new species for the department of Pasco in Peru.

47-56

Authors: Luz Adriana Velasco, Darío Vega, Ernesto Acosta, Judith Barros

In order to validate and optimize the protocol used for the spawning induction and fertilization of the mangrove oyster Crassostrea rhizophorae in Colombia, the reproductive cycle of natural populations from the Ciénaga de Mallorquín, was examined. Two experiments of induced reproduction were performed. In the first one, the effect of two spawning induction techniques (“Colombian” and “Cuban”) were compared based on the spawning response time, the fecundity and the percentages of spawned organisms. In the second experiment, the influence of two fertilization systems (“grouping” and “individual”) was evaluated, in terms of the percentages of oocyte fertilization and larvae D as well as larval growth and survival. Populations studied xhibited a semiannual reproductive cycle, the highest proportion of organisms in mature sexual state were obtained between June and July, coinciding with the beginning of the rainy season. The ercentage of spawned organisms was significantly higher using the Colombian spawning induction technique. The spawning response time was lesser in animals induced by the Colombian technique and the fecundity was not affected by the spawning inductor. Higher values of oocyte fertilization and larval growth were obtained with the grouping system of fertilization. Nevertheless, embryonic and larval survival values were similar for both treatments. In conclusion, the induced reproduction of C. rhizophorae populations from Ciénaga de Mallorquín, could carried out during rainy season (between april and september), using the Colombian spawning induction technique and the grouping system of fertilization. However it is necessary to improve the incubation techniques and larval culture in order to increase survival and growth values.

63-76

Authors: Patricia Martínez-Nieto, Daniel G. García-González

Encenillo (Weinmannia tomentosa Lf) and pagoda (Escallonia myrtilloides Lf) are dominant native tree species that can be found in the forests of the complex Andean Guerrero (Cundinamarca, Colombia). Forty two phosphorus-solubilizing bacteria and 125 nitrogen-fixing strains were isolated from the rhizosphere of these trees, out of which the microbial strains presenting the best five results of dissolution of phosphate and acetylene reduction by plant species were selected. The diazotrophic strains selected were identified as close to Enterobacter gergoviae, Alcaligenes sp. (E13C and E12E strains), Enterobacter sp. (E14C.2 strain), Pseudomonas sp., Sphingomonas sp., Paenibacillus sp., Achromobacter sp., Flavobacterium adoratum, and Klebsiella pneumoniae, and as phosphate-solubilizingbacteria near to Pantoea agglomerans, Pantoea sp., Brevudimonas sp., Enterobacter sp. (E6C.1 strain), Burkholderia cepacia, Arthrobacter sp., Aeromicrobium sp., Corynebacterium sp., Pimelobacter sp. and Micrococcus sp. In order to perform preliminary in vivo tests with the chosen microorganisms, it was inoculated bacterial mixture to encenillo and pagoda seedlings and evaluated their longitudinal growth for three months under greenhouse conditions. The major averages were obtained with the inoculation of Enterobacter gergoviae and Pantoea sp. in encenillo seedlings (average increase of 51% and 57% greater than the controls without microbial inoculation and sterile molasses medium, respectively) and the mixture of all selected bacteria in pagoda (Stimulation of 16% and 32% compared to controls molasses and without bacterial inoculation, respectively). The results showed that all the combinations using microbial inocula significantly stimulated longitudinal growth (Duncan multiple range test P<0.05). The synergism shown by co-inoculation of diazotrophic bacteria and phosphate solubilizing bacteria indicate the potential of these microorganisms as plant growth promoters and biofertilizers.

87-96

Authors: Maribet Gamboa

Spatial mobility between habitat fragments may present significant changes to the benthic organism system. Freshwater insects achieve dispersal using a manifold of mechanisms that may vary with respect to the characteristics of the individual or the environment; these can be categorized as passive or actives and have important implications in the processes of colonization, gene flow and evolutionary divergence. This review aims to explore studies of benthic insect dispersal based on empirical, theoretical approaches and examples of the dispersion in tropical and templates areas. We discuss how the spread can occur, its consequences and adaptations, as well as the advantages and disadvantages of conventional methods with respect to the molecular methods to study the dispersal of aquatic insects and when it is considered that human activities can prevent or reduce dispersion between different river systems, through the disruption and habitat fragmentation. In general, we looked for new questions to the mechanisms and patterns of dispersal in freshwater invertebrates and how they can be extrapolated to other taxa, since the selective pressures in aquatic systems as discrete habitats are similar.

104-107

Authors: Luis M. Rangel G., Luis A. Vidal V.

With the objective of knowing the microflora present in ballast water in the Santa Marta bay, samples were realized in 34 ships, between January and September of 2006. Stephanopyxis niponnica was found in two coal ships coming from the United States. The presence of this species of biogeographic distribution for cold waters, demonstrates the transport and potential introduction of exotic species to the region of Santa Marta via ballast water.